Vehicle data recording system

ABSTRACT

A vehicle data recording system has connections to one or more analog sensors, and stores data from the sensor(s) in a memory during laps of a track. The system provides for analog/digital conversion for converting analog data from the sensor(s) into digital data, and triggers a procedure for storing of the data in memory. Periods of storing of the data in memory are automatically started and stopped. The system stores in memory a set of data for a datum period and has means for storing further sets of data in a memory. A set of data stored during a first period is compared with a set of data stored during a further period and one of the sets of data is selected for retention in memory in accordance with a predetermined algorithm. The retained set of data is compared with the datum set and differences between the datum set and the selected set are output.

The present invention relates to a vehicle recording system and, moreparticularly, to an on-board computer designed for racing cars.

In order to provide information to the driver, engineers etc. of aracing car team, it is desirable to record data relating to themovement, speed, and other operational factors for subsequent analysis.

According to the present invention there is provided a vehicle datarecording system for connection to one or more analog sensors, and forstoring data from the sensor(s) in a memory during a plurality of chosenperiods, the system comprising:

analog/digital conversion means for converting analog data from thesensor(s) into digital data;

means for triggering a procedure for storing of the data into memory;

means for automatically starting and ending periods of storing of thedata in memory;

means for storing in memory a set of data for a datum period;

means for storing further sets of data in a memory;

means for comparing a set of data stored during a first period with aset of data stored during a further period and selecting for retentionin memory one of the sets of data in accordance with a predeterminedalgorithm; and,

means for comparing said retained set of data with the datum set andoutputting differences between said datum set and said selected set.

Preferably, the means for automatically starting and ending periods ofstoring of the data in memory comprises;

a transmitter for transmitting a beacon signal;

a receiver for monitoring for the presence of the beacon signal; and,

means responsive to the receipt of the beacon signal to indicate the endof one set of data and the start of a further set. The means fortriggering a procedure for storing of the data into memory may include amanually operable switch actuable by the driver of a vehicle in whichthe system is installed.

Furthermore, the means for displaying the differences between the datumset and the selected set may advantageously include a printer removablyattachable to the system.

One example of a system according to the invention will now be describedwith reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of the front face of adisplay/processor unit of the system;

FIG. 2 is an example of a lap report produced by the system;

FIGS. 3A and 3B are diagrammatic representations of the system circuitand arrangement on a car; and,

FIG. 4 is a flow diagram of the system in use.

The electronic data recording system has three functions. Firstly, itprovides all the facilities of conventional race car dash mountedinstrumention, although with added features such as memory and automaticwarnings. Secondly, it can be used as a data-logger capable of storinglarge quantities of information from many different types of sensors.Thirdly, the system can produce printed "lap reports" as soon as the carreturns to the pit lane. These serve the purpose of quantifyingmechanical changes in such a way so that the race engineer can see whereon the track, and by how much, the car has gone quicker or slower afterits set up has been altered.

The main display/processor unit 100, which houses most of the electroniccomponents, also has an LCD display 124 which provides the driver with atachometer 201 and three alphanumeric displays 202-204. A nine-positionrotary switch 205 allows the user to switch between different displayreadings as required. Warnings are automatically issued by the system asnecessary, for example a drop in oil pressure would trigger an alarm nomatter what the display was set to read. Such warnings must beacknowledged by the driver before the display reverts to its previousreading.

The system can be used to log data continuously on plural independentchannels (up to forty channels are possible with an expansion boardadded). The data acquired can be off-loaded from the system to a hostpersonal computer. Software has been written to allow the user toanalyze data at leisure on a personal computer should he so wish. Thedata is automatically divided into laps and can be displayedgraphically. The graphs obtained can be expanded and overlaid forcomparison.

The lap reports provide the race engineer and the driver with anassessment of the car's performance. This is primarily in terms ofspeed, although additional information on rpm, boost etc. may beprovided. The reports are presented either in an absolute manner or in aform which compares one lap to another. The purpose of the lap report isto provide the race engineer with immediate information giving him adeeper insight into the manner in which engineering changes on the carhave altered the car's performance. The onus is no longer on the driverto judge the relative merits of different set-ups. The instantavailability of the necessary information allows more objectivity to bebrought to bear on the task of optimizing the car's performance.

In order to enable enhancing and expanding upon the existingcapabilities of the system the hardware design of the system has beenimplemented to allow for considerable expansion of software in thefuture. Thus, once the system is in place any updates or customizationsto the system can be incorporated simply by changing an EPROM 123 (whichstores the software to control the system). This is a totallystraightforward process. In addition it is quite feasible to plug inelectronically controlled devices so that the box can act as the `brain`of an `active` system in order to provide actual control of variousengine management etc. functions.

Considering the system as a whole, the system offers a completeinstrumentation and analysis system with in-built power and flexibility.

Hardware Description

The system is comprised of a display/processor unit 100 complete withpower supply 101 and sensors for r.p.m 102, speed 103, pressure 104-106,temperature 107,108 and the `beacon` 109; a printer 110; and a tracksidebeacon 111. The latter two items are used by the pit crew. Thedisplay/processor unit and its sensor peripherals are permanentlyattached to a car 1, the boost, fuel and oil pressure sensors 104-106,the water and oil temperature sensors 107,108, the beacon detector 109and printer port 113 all being connected to the display/processor unitthrough a slave box 114 which also houses an inclinometer 115. Spareanalogue 116 and digital input lines are provided for additional sensorsdesired in a given car, e.g. ride height sensor, gearbox oiltemperature, throttle angle. The main system is designed to be part ofthe race car, and not an add-on just for testing.

The rpm sensor 102 passes signals to an rpm processor 120 into which areset values to represent the full scale reading of rpm permissible, thenumber of engine cylinders and the `red line` rpm point.

All other signals from sensors, together with a processed rpm signal arefed to a microcomputer 121 (in this example a `Tattletale V form OnsetComputer Corp.), which also has connections to an EPROM 122 and RAM 123.

The display/processor unit 100 is housed directly in front of thesteering wheel and contains a small screen 200 consisting of atachometer 201 and three alphanumeric displays 202-204 in addition tovarious other electronics components. On the left hand side of the boxis a large rotary nine-position switch 205 which is used to select thevarious facilities of the system. On the top lefthand corner of the boxis a push button 206 which the driver uses to control the chosenfacility, for example to reset the lap counter to zero. On the righthandside of the front face of the box is a small rectangular door 207. TheEPROM chip is situated behind this door.

When a full data logging test is required to be carried out anadditional logging box can be connected into the system via a connector112, signals from it being fed directly to the display/processor unit100. Depending on the configuration of the test this box may have quitea number of sensors stemming from its ports, for example, strain guages,linear transducers, proximity sensors which may be used to measureaccurately characteristics of the car such as suspension operation, rideheight etc. The main use for such data logging is during development ofa car.

The logging box is removable from the car when logging is notspecifically required. A special lead is plugged into the display andlogging boxes, connecting the two and allowing them to communicate. Whenthe two boxes are connected in this way the driver or engineer can usethe display/processor unit 100 controls to set parameters for thelogging box. In turn, the logging box can send data to the displayscreen. The display/processor unit 100 also has four logging channels ofits own. Thus some data logging can be performed without using thelogging box, obviating the need to fit the logging box at all whenperforming simple tests.

The printer 110 also plugs into the display/processor unit 100 via aprinter port 113 and the slave box 114 situated in the side of one ofthe car's sidepods 2. As the car 1 comes to a halt in the pit lane theengineer can simply plug the printer cable into the car's printer port113 and the system will immediately print out a lap report.

An optional data buffer/display unit 110' may be connected to theprinter port in place of (or as shown, in front of) the printer 110, andthis includes a RAM to which data, which would normally be outputted bythe system to the printer, can be stored temporarily anddisplayed/previewed on a liquid crystal display for instant analysis ofresults. The data can then be outputted to the printer 110 or to apersonal computer for long term storage/analysis of the data. Theattachment of the buffer/display unit 110' without the printer reduceswaiting time at the trackside as data can be downloaded to the unit muchmore quickly than it can to a printer and also allows quicker feedbackto the driver after analysis of the results on the display.

The beacon 111 is placed beside the track and transmits a signal (whichin the present example is an infra-red signal at a frequency of 950 nm,pulsed at 4 kHz and with a 1% duty cycle) which is received by thedetector 109 each time the car passes the beacon. The detector containsan optical band pass filter at 950 nm±approx 20 nm, a high passelectrical filter and a circuit for determining a sequence of n pulsesfor which the spacing is ±2% of the normal pulse spacing. This enablesthe software from the EPROM to calculate lap times and to divide thedata it has acquired into segments corresponding to one lap.

A personal computer (not shown) is used to analyze data logged by thelogging box (or by the display/processor unit 100). The computer can beplugged into the system via the printer port 113 and the operator thenuses the computer to transfer data from the system to the computer. Oncetransferred in this way the data can be stored permanently on thecomputer's hard or floppy disks and analysed at any time.

Basic Operation

The system is controlled by the user by means of the two switches205,206 mounted on the display/processor unit 100. The rotarynine-position switch 205 enables the user to select the variousinstrumentation, lap report and data logging options, and thepush-button switch 206 is used to set up and control these differentoptions.

Each of the nine positions of the nine-position switch 205 correspondsto a function or set of functions. When the user selects a new switchposition the current screen display is cleared and the screen displaysshow a message informing the user of the new position number. Thismessage takes the form of the words "NOW AT" and the position number.The message is cleared after half a second and the selected displayappears.

The push-button switch 206 can be used in three ways. Firstly, bypressing the button down momentarily, the user can either control thefunction which he has selected, or, if he has chosen a nine-positionswitch 205 setting with more than one option, switch between or selectthe functions in turn. Secondly, holding the switch down for more thanone-and-a-half seconds but less than five seconds performs a RESET. Thiswill set a given function to zero, for example the lap-counter. As soonas the word "RESET" appears in the lefthand text window 202 the switchmay be released. Thirdly, holding the switch down for more than fifteenseconds performs a MASTER RESET. This allows a fundamental change to beimplemented, for example the system's internal circuit map can be set upfor a new race track by performing such a reset. After the switch hasbeen held down for five seconds the display counts down from ten tozero. When the countdown reaches zero the word "MASTER" appears on thedisplay followed by the word "RESET". If the switch is released beforezero is reached (i.e. before fifteen seconds has elapsed in total), thesystem assumes that neither a RESET nor a MASTER RESET was intended andcontinues as if the switch had not been pressed. For some settings ofthe nine position switch 205 RESETS and/or MASTER RESETS areinappropriate and depressing the push-button switch 206 for extendedperiods will have no effect.

The Display

The display/processor unit 100 screen consists of an LCD display 124which provides a tachometer 201 in the form of a bargraph and threealphanumeric displays 202-204. The tachometer 201 is permanently on. Thethree alphanumeric displays are referred to throughout as the maindisplay, the top display and the lefthand display as shown in FIG. 1.These convey information to the user either in combination with oneanother or independently depending on the selected function. The usercan also if he wishes have them remain blank.

Instrumentation

This section describes the ways in which the system fulfils the functionof an instrumentation system. The bar-graph tachometer 201 ispermanently on. The three alphanumeric displays 202-204 provideinformation as determined by the driver's use of the display/processorunit switches. The driver can choose to look at various readings byselecting certain settings of the nine-position switch 205. In additionthe system automatically generates warnings when critical conditionsoccur, for example when the water temperature rises to too high a level.

Switch Position One--Timer, Stopwatch and Lap Counter

The screen displays a stopwatch, a timer to time qualifying sessions anda lap counter. The stopwatch uses the main display 203, the lap counterthe top display 204 and the session timer the lefthand display 202.

The stopwatch automatically times each lap and is triggered and reset bythe trackside beacon 111. The lap time, displayed in minutes, secondsand hundredths of a second, is updated as soon as the car passes thebeacon. Thus at any given time the lap time of the previous lap isshown.

The lap counter and the timer are controlled together. Initially thelefthand display 202 shows the text "TIMER" and the top display 204shows the text "LAP 0". One press of the push-button switch 206 erasesthe "TIMER" message and starts both the lap counter and timer from zero.The next press of the switch resets them to zero and restarts them. Oncestarted the lap counter is incremented each time the car passes thebeacon and the session timer counts the minutes since the restart. Thelap counter will count up to a maximum of 999 laps.

A RESET resets both the timer and the lap counter to zero withoutrestarting them. The initial text messages "TIMER" and "LAP 0" aredisplayed. The stopwatch is reset to zero but continues to be triggeredand reset by the beacon. A MASTER RESET in this setting of thenine-position switch 205 will have no effect.

The lap counter and the timer will both continue to function even if thenine-position switch 205 is moved from position one. Their respectivedisplays will reappear showing their current values if the nine-positionswitch 205 is subsequently turned back to position one.

The initial screen will be seen the first time that the user turns toswitch position one after switching the system on or performing a MASTERRESET (when in another switch position), as well as after a RESETperformed in switch position one.

Switch Position Two--Core Instrument Readings

Switch position two allows the driver or the race engineer to check thefour core readings: water temperature, oil temperature, oil pressure andfuel pressure (boost in the case of turbo-charged cars).

The lefthand display 202 reads "WATER", "OIL-T", "OIL-P", "FUEL" (or"BOOST") as appropriate. The top display 204 shows an appropriatemaximum or minimum reading by which to judge the current reading. Thesemaxima and minima are described below. The main display shows thecurrent reading in engineering units. The water and oil temperatures areshown in degrees centigrade, the oil and fuel pressures in PSI and theboost pressure in inches of mercury.

The driver or the engineer can switch between the four readings bypressing the push-button switch 206. Each press of the switch selectsthe next reading in turn, the display sequence cycling back to watertemperature after fuel/boost pressure.

Water Temperature

The top display 204 shows to the nearest integer the maximum watertemperature in degrees centigrade so far encountered. When the car stopsand restarts the maximum is updated to the current reading after oneminute to allow for the rise in water temperature whilst the car wasstationary. Updating of the maximum is disabled while the car isstationary. The main display shows the current water temperature to thenearest degree centigrade.

Oil Temperature

The top display 204 shows to the nearest integer the maximum oiltemperature in degrees centigrade so far encountered. When the car stopsand restarts the maximum is updated to the current reading after oneminute, as in the case of the water temperature, to allow for the risein oil temperature whilst the car was stationary. Updating of themaximum is disabled while the car is stationary. The main display 203shows the current oil temperature to the nearest degree centigrade.

Oil Pressure

The top display 204 shows to the nearest integer the minimum oilpressure in PSI so far recorded with the engine running at more than8000 RPM since the system was switched on. This display is activecontinuously. The main display 203 shows the current oil pressure in PSIto the nearest integer.

Fuel Pressure

The top display 204 shows to the nearest integer the minimum fuelpressure in PSI so far recorded with the engine running at more than 750RPM since the system was switched on. This display is activecontinuously. The main display 203 shows the current fuel pressure inPSI to the nearest integer.

Boost Pressure

The top display 204 shows to the nearest integer the minimum boostpressure in PSI times ten so far recorded with the engine running atmore than 8000 RPM since the system was switched on. This display is notactive whilst the car is stationary. The main display 203 shows thecurrent boost pressure to the nearest tenth of a PSI.

Switch Position Three--Speed Information/Clear Screen

This switch position has two options. The first option relaysinformation on the car's speed, the second option clears the top andmain display 203s leaving the driver with no distractions. The drivercan switch between the two options by pressing the push-button switch206.

Option One--Speed Information

The lefthand display 202 shows the text "SPEED", the top display 204shows the fastest speed attained on the previous lap and the maindisplay 203 shows local speed maxima and minima to the nearest tenth ofa MPH. Displaying the most recent maximum and minimum speeds gives thedriver a measure of how well he has taken a corner. As soon as the car'sspeed begins to increase after the slowest part of a corner the minimumspeed reached is displayed. Subsequently, as soon as the car's speedbegins to decrease after peaking on the following straight, the maximumspeed attained is displayed.

Option Two--Clear Screen

In this mode the top and main display 203s are blank while the lefthanddisplay 202 shows appropriate text. Thus the driver has no distractions.

Switch Position Four--Analog Readings

This switch position allows the user to inspect the readings from thedisplay/processor unit's analog input channels. The lefthand display 202contains text identifying the input, the main display 203 shows thereading and the top display 204 is blank. The user switches between thereadings by pressing the push-button switch 206. The various readingsare described below. In this switch position RESET and MASTER RESET arenot enabled. The readings displayed are sampled and updated five times asecond.

Battery Level

The lefthand display 202 reads "VOLTS". The main display 203 shows thebattery voltage to the nearest tenth of a volt.

Box Temperature

The lefthand display 202 reads "TEMP". The main display 203 shows thesystem's internal temperature to the nearest degree centigrade.

`Gyroscope`

The lefthand display 202 reads "GYRO". The main display 203 shows theinternal `gyro` (used for automatically obtain a map of the track forthe lap report) reading on a scale of 0 to 1023.

Front Right Ride Height

The lefthand dislay reads "FT-1". The main display 203 shows the frontright ride height on a scale of 0-1023.

Front Left Ride Height

The lefthand dislay reads "FT-2". The main display 203 shows the frontleft ride height on a scale of 0-1023.

Rear Right Ride Height

The lefthand dislay reads "Rr-1". The main display 203 shows the rearright ride height on a scale of 0-1023.

Rear Left Ride Height

The lefthand dislay reads "Rr-2". The main display 203 shows the rearleft ride height on a scale of 0-1023.

Warnings

The system continually monitors the four core readings and the batterylevel. A warning is issued to the driver should any of the followingconditions occur:

1) Oil pressure too low.

2) Water temperature too high.

3) Oil temperature too high.

4) Boost or fuel pressure too low.

5) Battery level too low.

When one of these conditions is detected the display is instantlycleared and the problem reading is then automatically shown to thedriver so that he can monitor its progress. The lefthand display 202contains text identifying the critical reading. Hence this will sayeither "WATER", "OIL-T", "OIL-P", "FUEL", "BOOST" or "VOLTS". The maindisplay 203 shows the reading. The reading is constantly updated untilthe driver acknowledges the fault by pressing the push-button switch206. The system then raises or lowers the appropriate threshhold valueso that a further warning will not be issued until a furtherdeterioration of the condition has taken place. The previous display isthen restored. Should two or more warning conditions occursimultaneously, they are processed according to the order of precedenceshown above. When one warning is acknowledged the next is displayed.

The threshhold values in comparison with which these warnings are issuedcan be set using switch position five.

Switch Position Five--Setting the Threshold Values

This switch position allows the user to change threshhold valuesassociated with the system warnings. The threshhold values that may bealtered are maximum water temperature, maximum oil temperature, minimumoil pressure and minimum boost pressure. A MASTER RESET transferscontrol to a host personal computer which is connected via the cableplugged into the car's printer port 113. The host computer is then usedto alter the threshhold values as desired. A RESET allows the user todispense with any changes to these values that have been made and revertto the original values.

Switch Position Six--Calibration

This switch position is used when calibration or recalibration ofsensors is required, for example, after replacement of a worn or damagedsensor.

Switch Position Seven--Road speed

This switch position simply allows the main display 203 to show theactual instantaneous speed of the car over the road surface, thusfunctioning as an additional or alternative speedometer.

The Lap Report

The purpose of the lap report is to provide the race engineer withimmediately available information on the way in which engineeringchanges made to the car have affected the car's performance. The systemcan produce six different types of lap report according to the needs ofthe engineer. The system references changes in the car's performance toa previous fast lap of the circuit, known as the datum lap, using aninternal map of the circuit which it automatically obtains on the firstouting at a new venue. In order to furnish the system with an internalimage of the circuit the initialisation procedure described below mustbe carried out. The report produced is always of the fastest lap of themost recently completed outing, an `outing` being an uninterruptedsequence of laps.

FIG. 4 is a flow diagram of the steps involved.

On arrival at a new race track the first task to be accomplished is toset the two parameters necessary for the lap reporter to function--thewheel circumference and the number of corners on the circuit. These areset using switch position eight. The user performs a MASTER RESET andthen selects the appropriate value for each parameter by pressing thepush-button switch 206 as the display cycles through the possible valuesof each parameter. This is described in more detail below. The driverthen drives the car round the track, aiming to achieve a fast lap on theracing line with no extraneous turns or swerves (e.g. overtakingmanoeuvres). This lap is known as the mapping lap and enables thecomputer to form its internal image of the circuit. When he has driven asuitable lap he should straightaway press the push-button beforebringing the car to a halt. Pressing the button while the car is inmotion selects the most recent, completed lap as the mapping lap.Pressing the button after the car has stopped selects the fastest lap sofar as the mapping lap. As soon as the mapping lap has been set and thecar has returned to the pit lane, the race engineer plugs the printer110 or printer buffer/display 110' in to the printer port 113 andobtains the mapping data sheet described below.

The Datum Lap

Of the six available types of lap report, two, including the standardlap report, present the data relative to a previous lap known as thedatum lap. The system automatically selects the fastest previous lap asthe datum lap, updating it every time the driver drives a faster lap.However, there are situations in which this is not appropriate, forexample if it has been raining, and so the facility exists to eitherprevent a new fastest lap from becoming the datum lap or to force a lessfast lap to become the new datum lap. This involves using switchposition eight and pressing the push-button switch 206 in response tothe prompts "VETO?" and "FORCE?" respectively. This is described in moredetail below.

Switch Position Eight--Setting Lap Report Parameters And Choosing TheDatum Lap

To set the lap report parameters the user switches to switch positioneight and performs a MASTER RESET. The system responds with the message"SET UP REPORT", the text "SET UP" appearing in the top display 204 andthe text "REPORT" appearing in the lefthand display 202. The userresponds by pressing the push-button switch 206. The message "FIX BENDS"then appears, the text "FIX" in the lefthand window, the text "BENDS" inthe top window. In the main display 203 a counting sequence is started,beginning at three and going up to twenty-five. Each number remains onthe display for one second. The user presses the push-button switch 206when the number corresponding to the number of corners on the circuitappears. If no number is selected by the user the counting sequencerestarts from three again. When the user has selected the number ofbends the message "FIX WHEEL" appears, the text "FIX" in the lefthanddisplay 202 and the text "WHEEL" in the top display 204. Again acounting sequence appears in the main display 203. The user presses thepush-button switch 206 when the appropriate wheel circumferencemeasurement appears on the screen. The screen then flashes several timesbefore displaying the message "SET MAP", the text "SET" in the lefthanddisplay 202, the text "MAP" in the top display 204. The driver thenattempts to drive a suitable mapping lap. When he is satisfied that hehas driven a suitable lap he can make it become the mapping lap bypressing the push-button switch 206. If the switch is pressed while thecar is still in motion the most recently completed lap becomes themapping lap. If the car has come to a halt before the driver presses theswitch, pressing the switch selects the fastest lap driven since theMASTER RESET as the mapping lap.

The datum lap is normally the fastest lap driven so far. If on his mostrecent outing the driver drives a faster lap, the lap report producedwill be relative to the old datum lap but the new, faster lap willautomatically become the new datum lap. The engineer can use switchposition eight to override this process.

If the fastest lap on the most recent outing was faster than the datumlap, turning to switch position eight yields the following: the lefthanddisplay 202 shows "LAP nn" where nn is the lap number of the last lap,the main display 203 contains the lap time of the new fastest lap andthe top display 204 shows the text "VETO?". Pressing the push-buttonswitch 206 prevents the new fastest lap from becoming the datum lap, andthe message "VETOED" appears in the top display 204.

Alternatively, if the fastest lap on the most recently completed outingwas slower than the present datum lap, turning to switch position eightyields the following: the lefthand display 202 shows the lap number asabove, the main display 203 shows the lap time of the fastest lap of themost recently completed outing, and the top display 204 contains thetext "FORCE?". Pressing the push-button switch 206 makes this lap, thefastest of the most recent outing, the new datum lap. The message"FORCED" appears in the top display 204.

A RESET in this switch position changes the screen, showing the text"DATUM", in the top display 204, the lap number of the lap on which thecurrent datum lap time was set in the lefthand display 202 and the datumlap time in the main display 203. This screen display lasts for fiveseconds, then the previous information reappears. This last displayformat is also what one will see in switch position eight after theouting on which the mapping lap has been set, since there are noprevious outings for comparison.

The Mapping Data Sheet

When the car comes to a halt after the outing on which the mapping laphas been set the engineer can obtain a printout showing the way in whichthe system has chosen to divide the track into segments. A segmentconsists of either a corner or the straight between two corners. Foreach segment the following information is given: the length of thesegment in meters, the time taken for the car to cover the segment, themaximum or minimum speed for straights and corners respectively, and thesegment type. Segments are classified as either straights, fast corners,medium corners or slow corners. The engineer may then use thisinformation to supplement that shown on the pre-printed sheet. To obtainthis printout the user loads the printer with a plain piece of A5 paperand plugs the printer cable into the car's printer port 113 ot thebuffer/display unit 110'. Printing proceeds automatically.

The Pre-Printed Sheet

The standard lap report (see FIG. 2) is printed on a pre-printed sheet300. This sheet shows a map 301 of the circuit with the corners numberedand has sections in which the system prints speed changes 302 and a lapsummary 303. The total lap time and the straight-line speed are shownand compared with those of the datum lap. There is also a space setaside for the engineers handwritten comments.

In the speed change section the system lists in order of magnitude thefive most significant speed changes on the lap relative to the datumlap. These may be on straight segments, corner segments or on entry orexit to corner segments. Corner entry and exit times are denoted by thesuffixes IN and OUT respectively.

In the lap summary section the number of speed gains on entry and exitto corners of each type is printed.

Obtaining The Standard Lap Report

Obtaining the standard lap report is a straightforward process providingthe mapping lap has been set. The printer is loaded with a pre-printedlap report sheet. As the car comes to a halt in the pit lane after anouting, the user simply plugs the printer cable into the car's printerport 113. Alternatively, the printer buffer/display 110' is plugged into the port 113 and data transferred to it, the printer later beingplugged into the unit 110'. Printing then takes place automatically.

The Different Types Of Lap Report

The system prints out (or displays on the printer buffer/display) areport on the fastest lap of the most recent outing in the form selectedby the user. The engineer can select the desired form using switchposition nine. To obtain the standard lap report it is not necessary toswitch to position nine. However, if for example a second copy of it isrequired, it can be obtained using switch position nine. Only thestandard lap report (option one) uses the pre-printed sheet. For allother types of lap report the printer must first be loaded with a plainsheet of A5 paper before the printer cable is plugged into the printerport 113. The choices of lap report are are as follows:

1) "LAP-R"

Report showing times and speeds of fastest lap of last outing relativeto the datum lap. (The standard lap report).

2) "LAP-A"

Report showing actual times and speeds of fastest lap of last outing.

3) "Spd-R"

Graph showing speed versus distance for fastest lap of last outingrelative to the datum lap.

4) "Spd-A"

Graph showing actual speed versus distance for fastest lap of lastouting.

5) "RPM"

Graph showing RPM versus distance on fastest lap of last outing.

6) "BOOST"

Graph of boost pressure versus distance on fastest lap of last outing(if desired).

Switch Position Nine--Selecting The Lap Report Format

In switch position nine the left hand display cycles through theavailable choices (LAP-R, LAP-A etc. as listed above) displaying eachfor one second. To select the desired format the user presses thepush-button switch 206 while the required option is showing. The maindisplay 203 then flashes until the printer is plugged in or thenine-position switch 205 setting is changed. When printing is completedthe left hand display again cycles through the available choices.

The Push-Button Switch

The push-button 206 switch located on the top left hand side is used ina number of different ways:

(a) A `click`

In the majority of cases the button is just pressed down momentarily inorder to make a selection or to page through the different optionsavailable on each setting of the nine-position switch 205. The momentthe button is pushed down, the lower left display changes from whatevertext it is presently owing to just a line; `----------`. This gives theoperator feedback that the press has worked ok. If the button isreleased within 1.5 seconds the computer interprets the press as amomentary press.

(b) A `RESET`

Sometimes it is necessary to reset a certain function, for instance whenthe system is counting laps and it is required to reset the counter backto zero. This is achieved simply by holding the button down for as longas it takes the word `RESET` to appear in the left hand text window.

In order for the system to tell the difference between a momentary pressand a long `reset` press the software constantly monitors the switch. Ifit detects a transition from switch up to switch down it first clearsthe left display and then sets a timer in motion, a transition from downto up halts the timer. If the timer reads less than 1.5 seconds thesystem interprets the press as a momentary one. If greater than 1.5seconds a `reset` press is assumed and `RESET` is sent to the display. Alittle practise makes the difference clear. This form of switch press isonly appropriate to some of the available options.

(c) A `MASTER RESET`

There is one additional type of press, only used when very deliberateaction is required, for instance when it is needed to tell the systemthat the next run is at a new circuit. This is called a master reset andis only appropriate to a few settings. Here one holds the button downfor a full 30 seconds before releasing. The display will show `RESET` inthe left hand display, and after about 5 seconds the main display 203will start to count down to zero at one second intervals. If the buttonis released at any time while the count down is showing it is as thoughthe button had never been pressed at all. (Thus giving a way out if onechanges one's mind about giving the machine a normal reset.) If onepersists the count will eventually reach zero, the display will flash`MASTER` and then `RESET`, and a master reset will have been achieved.As with a normal `RESET` the master reset is only appropriate to certainoptions.

We claim:
 1. A vehicle data recording system for connecting to at leastone analog sensor on the vehicle, and for storing sets of data therefromduring a plurality of chosen periods of operation on a course, thesystem comprising:an analog/digital converter responsively coupled tothe at least one sensor for converting analog data therefrom intodigital data; a memory responsively coupled to the analog/digitalconverter for storing the digital data; gating means operatively coupledto the memory for initiating storage of the data into said memory; meanspartly on the course and partly on the vehicle and operatively coupledto the memory for initiating start and end signals for respectivelystarting and ending periods of storing of the corresponding set of datain the memory; means operatively coupled to the memory for selectivelystoring in the memory a set of said data for a datum period; meansoperatively coupled to the memory for storing further sets of data inthe memory; means responsively coupled to the memory for comparing a setof data stored during a first period with a set of data stored during afurther period and selecting for retention in memory one of the sets ofdata in accordance with a predetermined criterion; and, meansresponsively coupled to the memory for comparing said retained set ofdata with the datum set and outputting differences between said datumset and said selected set.
 2. A system according to claim 1, wherein themeans for initiating start and end signals for respectively starting andending the periods of storing the data in memory comprises:a transmitteron the course for transmitting a beacon signal; a receiver on thevehicle for monitoring for the presence of the beacon signal; and meansresponsive to the receipt of the beacon signal to indicate the end ofone set of data and the start of a second set of data.
 3. A systemaccording to claim 1, wherein the gating means includes a manuallyoperable switch actuable by the driver of a vehicle in which the systemis installed.
 4. A system according to claim 1, wherein the means foroutputting the differences between the datum set and the selected setincludes a printer removably attachable to the system.
 5. A systemaccording to claim 1, wherein the means for outputting the differencesbetween the datum set and the selected set includes a databuffer/display unit which includes a RAM for storing data temporarilyand for at least one of displaying and previewing on an integral liquidcrystal display and outputting to a printer and computer.
 6. A vehicledashboard instrumentation system in which a plurality of vehicle mountedsensors are adapted to generate respective data comprising:a data memoryresponsive to the sensors for storing the data in a plurality of classesduring corresponding periods; display means responsively coupled to thememory operative for displaying said data; selector means operativelycoupled to the memory operative for selecting which of said classes ofdata is displayed by said display means; initiator means operativelycoupled to the memory for initiating storage of a plurality of sets ofsaid classes of data in said memory during a plurality of saidcorresponding periods; means operatively coupled to the memory operativefor starting and ending individual ones of said periods of storing saidsets of data in memory; means responsively coupled to the memoryoperative for retaining in memory a datum set of data for a datumperiod; means responsively coupled to the memory operative for comparinga first set of data stored during a first period with a second set ofdata stored during a second period and selecting and retaining in memoryat least one of the first and second sets of data; and, meansresponsively coupled to the memory operative for comparing said retainedset of data with the retained datum set and outputting and displayingdifferences between said datum set and said selected set.
 7. A vehicledata recording system, for connection to at least one sensor on thevehicle and for storing sets of data therefrom during a plurality ofcorresponding lap periods of recurring operation on a coursecomprising:a memory for receiving the data; signaling means partlylocatable in the vehicle and partly locatable on the course at aposition for producing an indication each time the vehicle has passedsaid position; a gate responsive to the indication of said signalingmeans operatively coupled to the memory for initiating and terminatingselected periods for storage of a set of data into the memory for thecorresponding lap period each time the vehicle passes said position; aplurality of memory locations in said memory for storing a set of datafor each corresponding lap period; a selector coupled to the memory forselecting a datum period from said lap periods; a comparatorresponsively coupled to the memory for comparing data from the lapperiods with the data from the datum period and for producing an outputindicative of a difference therebetween, said comparator operativelycoupled to the selector for updating the datum period.